Hepatitis C virus (HCV) infection is a serious worldwide health concern, infecting approximately 2% of the population. It is the major cause of non-A non-B hepatitis. More than 70% of infected individuals develop a persistent infection, which frequently leads to chronic liver disease, cirrhosis, and hepatocellular carcinoma. It is the leading indicator for liver transplants in the world. The virus cannot be reliably cultured in cells, and there is no small animal model. For these reasons, HCV does not lend itself readily to the prescriptive methods of virological investigation. The available treatments for HCV infection are expensive, and the side effects are severe. HCV, an important human pathogen, is a difficult virus to study, to treat, or even to detect. The long-term goal of this project is to target regulation of viral translation for possible HCV-specific drug discovery and design that will overcome the limitations of existing treatments. Toward achieving this goal, we will characterize the natural regulatory mechanisms of translation used by HCV, specifically focussing on those that involve RNA structures in the internal ribosome entry site (IRES). Based on preliminary data, we hypothesize that stabilization of the RNA structure flanking the HCV start codon (specifically the structure defined by the HCV genome sequence nt 330-368) will inhibit initiation of HCV IRES-dependent translation. Such molecules represent lead compounds for drug discovery. Specific RNA structural elements from the HCV IRES will be used as targets for selection of strong binding molecules using several methodologies. These binding interactions will be biochemically characterized, and promising RNA ligands will be assayed for HCV IRES-specific translational inhibition, both in vitro and in vivo. One of the primary goals of this project is to develop assays for this research that will also be useful for future research in this lab.